Dielectric Spectroscopy of Biomolecules up to 110 GHz

Abstract

Radio-frequency fields in the GHz range are increasingly applied in biotechnology and medicine. In order to fully exploit both their potential and their risks detailed information about the dielectric properties of biological material is needed. For this purpose a measuring system is presented that allows the acquisition of complex dielectric spectra over 4 frequency decade up to 110 GHz. Routines for calibration and for data evaluation according to physicochemical interaction models have been developed. The frequency dependent permittivity and dielectric loss of some proteins and nucleic acids, the main classes of biomolecules, and of their sub-units have been determined. Dielectric spectra are presented for the amino acid alanine, the proteins lysozyme and haemoglobin, the nucleotides AMP and ATP, and for the plasmid pET-21, which has been produced by bacterial culture. Characterisation of a variety of biomolecules is envisaged, as is the application to studies on protein structure and function.

Dielectric spectroscopy technique for detection of human respiratory syncytial virus

“…The low‐frequency dispersion of ε r ′ below 0.6 GHz for both the RSV rNP and RSV rNP + antibody occur due to the different permittivities and conductivities of the bioparticle and the surrounding medium . A similar response can be found in the literature …”

“…In addition to ε r ′ information, the ε r ″ spectra for RSV rNP or RSV rNP + antibody shows the predominance of ionic loss ( ε rσ ″) below 1 GHz. This strong increase of ε r ″ below 1 GHz is a behavior typically observed in biological materials related to nucleic acid; either DNA or RNA . The RSV rNP is a biological material that is structurally associated with nucleic acids.…”

“…23 A similar response can be found in the literature. 15,16 The differences in ε r 00 among the RSV rNP + antibody, RSV rNP, and BSA solutions shows another distinguishable factor, as shown in Figure 7B. There are two types of dielectric loss mechanism called dipole loss (ε rd 00 ) and ionic loss (ε rσ 00 ).…”

“…The peak value of ε r ″ in RSV rNP, as shown in Figure B, is reduced when compared with that of DI water. A possible explanation for this is that a large portion of the water molecules bind to the strongly charged nucleic acids, NP, in this article. This also changes the dipole relaxation time (τ), in turn with the relaxation frequency ( f c ).…”

“…The open‐ended coaxial line is quite useful when measuring materials submerged in a liquid or in liquid state, as shown in Figure A. An open‐ended coaxial line has been used to measure and characterize aqueous Salmon sperm DNA solutions, various proteins (lysozyme and hemoglobin), and nucleic acids (the nucleotides AMP and ATP, and the plasmid pET‐21) . Although the dielectric properties of the Tobacco Mosaic Virus were measured in the MHz range using time domain dielectric spectroscopy, to the best knowledge of the authors, no complex permittivity spectra of a specific virus in aqueous solution over a wide frequency range were reported.…”